Brain temperature and hippocampal function

Andersen, P.; Moser, Edvard I

doi:10.1002/hipo.450050602

Cited by 152 publications

(101 citation statements)

References 32 publications

(22 reference statements)

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“…Change in brain temperature is a factor that affects various neural functions ranging from the activity of ionic channels and receptor sensitivity (Thompson et al, 1985;Rosen, 2001) to such global neuronal alterations as release and uptake of neurotransmitters (Andersen and Moser, 1995;Xie et al, 2000). Thus, the METH-induced metabolic activation suggested by our temperature measurements could be a "common denominator" for various abnormalities in neural functions (i.e., thermal stress, oxidative stress, abnormal transmitter release, decrease in ATP, etc.)…”

Section: Meth Induces Pathological Metabolic Neural Activation and Hymentioning

confidence: 85%

Brain Hyperthermia Is Induced by Methamphetamine and Exacerbated by Social Interaction

2003

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Hyperthermia is a symptom of methamphetamine (METH) intoxication and a factor implicated in neurotoxicity during chronic METH use. To characterize the thermic response to METH, it was injected once daily into rats at increasing doses (0, 1, 3, and 9 mg/kg, s.c.) while brain [nucleus accumbens (NAcc), hippocampus] and body (deep temporal muscle) temperatures were continuously monitored. METH produced dose-dependent hyperthermia, with brain structures (especially the NAcc) showing a more rapid and pronounced temperature increase than the muscle. At the highest dose, brain and body temperatures increased 3.5-4.0°C above basal levels and remained elevated for 3-5 hr. Stressful and other high-activity situations such as interaction with a conspecific female are also known to induce a significant hyperthermic response in the rat. A combination of social interaction and METH administration was tested for additive effects. Male rats were exposed daily to a conspecific female for a total of 120 min, and METH was injected at the same doses 30 min after the initial contact with the female. An initial hyperthermic response (ϳ1.5°C) to social interaction was followed by a large and prolonged hyperthermic response (3.5-5.0°C, 5-7 hr at 9 mg/kg) to METH, which was again stronger in brain structures (especially in the NAcc) than in the muscle. Although the combined effect of the hyperthermic events was not additive, METH administration during social interaction produced stronger and longer-lasting increases in brain and body temperature than that induced by drug alone, heating the brain in some animals near its biological limit (Ͼ41°C).

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Section: Meth Induces Pathological Metabolic Neural Activation and Hymentioning

confidence: 85%

Brain Hyperthermia Is Induced by Methamphetamine and Exacerbated by Social Interaction

2003

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“…Perhaps the most significant and unique feature of the present experiment was the provisioning of a thermoneutral test environment in which body temperatures of infants at the ages used here are maintained at ϳ37°C (Blumberg et al, 1997). This feature of the experiment may be important for two reasons: First, hippocampal electrophysiological activity is influenced by local brain temperature (Andersen and Moser, 1995) and hippocampal slices from adult rats can be induced to exhibit theta-like activity only within a narrow thermal window of 33-37°C (Kowalczyk et al, 2001). Second, testing in an appropriate thermal environment permits the expression of many prolonged periods of REM (or active) sleep (Sokoloff and Blumberg, 1998), thereby maximizing the number and duration of artifact-free periods of hippocampal recording.…”

Section: Discussionmentioning

confidence: 99%

“…In total, these studies indicate that the neonatal rat does not, and perhaps cannot, produce hippocampal theta. However, in the two previous in vivo experiments, pups were tested in conditions that were not thermally controlled and thus were not ideal for the expression of REM sleep (Blumberg, 2001), thus raising the question of whether theta might be expressed under thermoneutral conditions (Andersen and Moser, 1995).…”

Section: Introductionmentioning

confidence: 99%

Hippocampal Theta in the Newborn Rat Is Revealed under Conditions That Promote REM Sleep

Karlsson

Blumberg

2003

J. Neurosci.

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Hippocampal theta activity, a high-amplitude, slow (4 -12 Hz) oscillation that occurs in a variety of behavioral contexts, is thought to emerge in infant rats only after 1 week of age. However, we report here that unanesthetized 2-and 4-d-old rats with electrodes implanted in the CA1 field of the hippocampus and tested in thermoneutral conditions exhibit theta activity. Moreover, this infant theta is characterized by the same neuronal bursting pattern and power spectrum that characterize theta in adults. Simultaneous measures of behavior and neck muscle tone indicated that bouts of theta occurred predominantly during periods of muscle atonia (with or without concurrent myoclonic twitching), indicative of REM sleep. In contrast, sharp waves were accompanied by startles (i.e., simultaneous and vigorous movement of all four limbs). These findings underscore the need for comprehensive in vivo investigations of the pharmacology, neural substrates, and behavioral correlates of hippocampal field activity in neonates.

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“…Our in vivo brain temperature measurements (SI Appendix, Fig. S11) showed >100 mW/mm 2 of 635-nm light could be delivered via the large-volume illuminator 1 mm from the source with <1°C temperature increase, a commonly accepted conservative limit for changes in brain function (49,(58)(59)(60). Preliminary tests showed that temperature increases peaked 1 mm away from the light source (SI Appendix, Fig.…”

Section: Significancementioning

confidence: 92%

FEF inactivation with improved optogenetic methods

Acker

Pino

Boyden

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

102

114

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Optogenetic methods have been highly effective for suppressing neural activity and modulating behavior in rodents, but effects have been much smaller in primates, which have much larger brains. Here, we present a suite of technologies to use optogenetics effectively in primates and apply these tools to a classic question in oculomotor control. First, we measured light absorption and heat propagation in vivo, optimized the conditions for using the red-light-shifted halorhodopsin Jaws in primates, and developed a large-volume illuminator to maximize light delivery with minimal heating and tissue displacement. Together, these advances allowed for nearly universal neuronal inactivation across more than 10 mm 3 of the cortex. Using these tools, we demonstrated large behavioral changes (i.e., up to several fold increases in error rate) with relatively low light power densities (≤100 mW/mm 2 ) in the frontal eye field (FEF). Pharmacological inactivation studies have shown that the FEF is critical for executing saccades to remembered locations. FEF neurons increase their firing rate during the three epochs of the memory-guided saccade task: visual stimulus presentation, the delay interval, and motor preparation. It is unclear from earlier work, however, whether FEF activity during each epoch is necessary for memory-guided saccade execution. By harnessing the temporal specificity of optogenetics, we found that FEF contributes to memory-guided eye movements during every epoch of the memory-guided saccade task (the visual, delay, and motor periods).primate | optogenetics | FEF | Jaws | memory-guided saccade T he frontal eye field (FEF) is an important brain area for making saccades to remembered locations. FEF neurons increase their firing rate during three epochs of memory-guided saccades: (i) target presentation, (ii) delay period, and (iii) motor preparation. Pharmacological inactivation of the FEF impairs memory-guided saccades (1-7), but because pharmacological inactivation inhibits all FEF neuronal activity, it is unclear if the FEF's role is specific to one or more task epochs (8,9). By selectively inactivating the FEF during each task epoch, we can determine whether visual-, delay-, or motor-related firing (or some combination of the three types of firing) contributes to memory-guided saccades.The ideal tool for this study is optogenetics, which allows for millisecond-precise, light-driven neuronal control. Unfortunately, although optogenetics is widely used to study functional physiology and disease models in rodents and invertebrates, technical challenges have limited the use of optogenetics in the nonhuman primate brain, which has a volume ∼100-fold larger than the rodent brain (10). Pioneering studies in monkeys reported small behavioral effects with excitatory (11-14) and inhibitory opsins (15-17). These studies used large light power densities (several hundreds of milliwatts per square meter to 20 W/mm 2 ) but illuminated only small volumes, at most 1 mm 3 , due to both the chosen wavelength and light-deliver...

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Brain temperature and hippocampal function

Cited by 152 publications

References 32 publications

Brain Hyperthermia Is Induced by Methamphetamine and Exacerbated by Social Interaction

Brain Hyperthermia Is Induced by Methamphetamine and Exacerbated by Social Interaction

Hippocampal Theta in the Newborn Rat Is Revealed under Conditions That Promote REM Sleep

FEF inactivation with improved optogenetic methods

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